The present invention relates to a linear guide for transmitting a torque between a tubular housing, which is defined by a longitudinal axis and rotatable about the longitudinal axis, and a shaft, which is received in the housing and movable in the direction of the axis in relation to the housing.
Linear guides for transmission of torques are used in the automobile industry for example for guiding racks or for guiding steering spindles in a steering column. Another use involves the guidance of gearshift shafts or gearshift rails in the transmission of motor vehicles.
U.S. Pat. No. 3,427,656 describes a linear guide having sets of axial rolling bearings which are arranged in the area of a radial plane of a shaft and are held in a tubular housing. The axial rolling bearings surround the shaft and have cup-shaped running disks for support on the shaft surface. As the shaft has a circular cross section, torque of the shaft cannot be transmitted to the housing. This conventional linear guide requires also the arrangement of a tensioning screw to pretension the sets of axial rolling bearings and to act in the area of a radial slot of the housing upon the housing.
German patent publication No. DE 196 19 449 A1 describes a linear guide having a rod or shaft with rollers bearing on the bearing surface of the shaft and which are rotatably supported in a carriage surrounding the shaft. The carriage is configured as a rectangular hollow profile with T-grooves that are exteriorly accessible, and by means of which other desired parts may be secured. For support of the rollers, bore holes are provided at the side walls of the hollow profile where rotational bearing, in particular roller bearings are disposed. Furthermore, at least one roller, respectively the bearing support of the roller requires a control device, preferably a set screw for snug adjustment of the roller against the shaft.
German patent publication no. DE 37 30 393 A1 discloses a torque transmitting connection for shaft parts that move axially within one another for use in a steering shaft of a motor vehicle. The linear guide has balls as rolling members which are received free from play in inner longitudinal grooves of the outer shaft part, on one hand, and in outer longitudinal grooves of the inner shaft part, on the other hand. In order to compensate manufacturing tolerances and to realize a smooth running without a need for refinishing works, when the shaft parts move axially relative to one another, the balls must be arranged in raceways of sheet metal which are placed in the longitudinal grooves and loaded radially under tension in relation to the longitudinal center axis of the shaft. Moreover, both shaft parts can be moved axially relative to one another only in a limited manner.
It would therefore be desirable and advantageous to provide an improved linear guide which obviates prior art shortcomings and which is simple in structure and cost-efficient while still being reliable in operation independent on dimensional tolerances of the tubular housing and the axially movable shaft.